Analog-to-digital converter with writable result register

Abstract

An analog-to-digital converter has a conversion section that converts an external analog signal to an internal digital signal, a digital input port that receives an external digital signal, and a result register. A selector controlled by a selection signal selects either the internal digital signal or the external digital signal for storage in the result register. The external digital signal can be written into the result register for test purposes, or to use the result register for general-purpose data storage.

What is claimed is: 
     
       1. An analog-to-digital converter circuit, comprising: an analog input port for receiving an external analog signal;   a digital input port for receiving an external digital signal having a plurality of parallel bits;   a first control port for receiving a first selection signal;   a second control port for receiving a second selection signal;   a conversion circuit coupled to said analog input port, for converting said external analog signal to an internal digital signal having a plurality of parallel bits;   a first selector coupled to said conversion circuit and said digital input port, said first selector receiving said external digital signal and said internal digital signal in parallel form, said first selector selecting one signal from said internal digital signal and said external digital signal in response to said first selection signal;   a second selector coupled to said conversion circuit and said digital input port, said second selector receiving said external digital signal and said internal digital signal in parallel form, said second selector selecting one signal from said internal digital signal and said external digital signal in response to said second selection signal;   first result register coupled to said first selector for storing the signal selected by said first selector;   a second result register coupled to said second selector for storing the signal selected by said second selector; and   a digital output port for parallel output of the signal stored in said first result register and the signal stored in said second result register.   
     
     
       2. The analog-to-digital converter circuit of claim 1, further comprising a plurality of analog input ports coupled to said conversion section in parallel. 
     
     
       3. The analog-to-digital converter of claim 1, wherein said analog-to-digital converter forms one part of a microcontroller. 
     
     
       4. The analog-to-digital converter circuit of claim 3, wherein said microcontroller includes a central processing unit which reads and writes data in said result register. 
     
     
       5. An analog-to-digital converter circuit, comprising: an analog input port for receiving an external analog signal;   a conversion circuit coupled to said analog input port, for converting said external analog signal to an internal digital signal;   a digital input port for receiving an external digital signal which is independent of the internal digital signal;   a first control port for receiving a first selection signal;   a second control port for receiving a second selection signal;   a first selector coupled to said conversion circuit and said digital input port, said first selector being responsive to said first selection signal for selecting one signal from said internal digital signal and said external digital signal;   a second selector canded to said conversion circuit and said digital input port, said second selector being responsive to said second selection signal for selecting one signal from said internal digital signal and said external digital signal;   a first result register coupled to said first selector, for storing the signal selected by said first selector;   a second result register coupled to said second selector, for storing the signal selected by said second selector; and   a digital output port for output of the signal stored in said first result register and the signal stored in said second result register.   
     
     
       6. The analog-to-digital converter circuit of claim 5, further comprising a plurality of analog input ports coupled in parallel to said conversion circuit. 
     
     
       7. An analog-to-digital converter circuit, comprising: an analog input port for receiving an external analog signal;   a conversion circuit coupled to said analog input port, for converting said external analog signal to an internal digital signal;   a digital input port for receiving an external digital signal which is independent of the internal digital signal;   a first control port receiving a first selection signal;   a first selector directly connected to said conversion circuit and said digital input port, said first selector being responsive to said first selection signal, for selecting one of said internal digital signal and said external digital signal;   a second selector directly connected to said conversion circuit and said digital input port, said second selector being responsive to said second selection signal, for selecting one of said internal digital signal and said external digital signal;   a first result register directly connected to said first selector, for storing the signal selected by said first selector;   a second result register directly connected to said second selector, for storing the signal selected by said second selector; and   a digital output port for output of the signal stored in said first result register and the signal stored in said second result register.   
     
     
       8. The analog-to-digital converter circuit of claim 7, further comprising a plurality of analog input ports coupled in parallel to said conversion circuit. 
     
     
       9. The analog-to-digital converter circuit of claim 7, wherein said analog-to-digital converter forms one part of a microcontroller. 
     
     
       10. The analog-to-digital converter circuit of claim 9, wherein said microcontroller comprises a central processing unit that reads and writes data in said first result register and said second result register.